Production method for ceramic porous material

ABSTRACT

To provide a method for producing a ceramic porous material which has a high strength, though it has a high porosity, and which is excellent in permeability without dust generation. In a ceramic porous material having a three-dimensional mesh-like skeleton structure with a large number of substantially spherical adjacent cells communicating with each other via communication holes, the crystal particle size at the rim of each communication hole in the skeleton structure is provided substantially equal to the crystal particle size in the other parts.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a ceramic porous material havinga bubble-like appearance to be used as a filter, a bubbler, a gassupplying member, a semiconductor producing device member, an artificialbone, a cell culturing supporter, an artificial organ, a catalystsupporter, or the like, and a production method therefor.

[0003] 2. Description of the Related Art

[0004] Conventionally, as a ceramic porous material of this kind, onehaving a three-dimensional mesh-like skeleton structure with a largenumber of substantially spherical adjacent cells (pores) communicatingwith each other via communication holes has been known (see the officialgazette of the Japanese Patent Laid Open Application (JP-A) No. 4-202071(Patent No. 2,506,502).

[0005] The ceramic porous material is produced by preparing a slurry bydispersing or dissolving in a solvent a ceramic powder and an organicsubstance to be hardened by the cross-linking polymerization, adding across-linking agent to the slurry, molding and hardening (gellationmolding) in an agitated and bubbled state, drying the compact and baking(fireing, sintering).

[0006] However, according to the conventional ceramic porous material,problems are involved in that the mechanical strength is low, dusts(particles) are generated, and the transmissivity is poor.

[0007] In order to find the cause of the problems, the periphery of thecommunication holes in the skeleton structure was observed with ascanning type electron microscope so that an abnormal form of crystalparticles forming the rim of the communication holes was observed.

[0008] That is, at the rim of the communication holes, single particlesof a cockscomb shape and a cactus shape were observed. Moreover, thefact that minute holes of the size equivalent to the crystal particlesize, communicating the adjacent pores were found at the rim part of thecommunication holes and the growth of the crystal particles arerestrained at the rim of the communication holes was found.

[0009] It can easily be assumed that the above-mentioned crystalparticle growth abnormal part became the breakage starting point whenthe external force was applied to the ceramic porous material so as tocause stress concentration, and furthermore, the cockscomb shaped andcactus shaped parts were peeled off so as to generate dusts.

[0010] Accordingly, it is considered that the abnormal form of thecrystal particle growth forming the rim of the communication holes isgenerated in the production process of the ceramic porous material.

[0011] That is, the cells of the slurry stage are formed by the liquidmedium containing the ceramic powder, and in most cases by the aqueousslurry. The slurry before hardening is moved by the surface tension andparts between the adjacent cells are partially thinned and broken so asto form the communication holes. The communication hole rims linking thecells accordingly formed are of a sharp shape because they are brokenafter thinning and the viscosity of the slurry at the time of breakingis high and the flowability after film breakage to rounding the rims islow. Or in the case of forming the communication holes by breaking thethin film at the time of expansion and shrinkage of the air in the cellsdue to the temperature change after drying, or the like, the smallpieces of the dried substances generated by the breakage can be adheredon the wall surface of the cells.

[0012] The average particle sizes of the crystal particles at the rim ofthe communication holes of the alumina ceramic porous material of the80% porosity (baked at 1,600° C. for 2 hours in the air), at a position2 μm away from the rim, and at a position 4 μm away from the rim were0.80 μm, 1.67 μm, and 1.81 μm, respectively, and it was 8.52 μm at aposition 100 μm away from the rim. The average particle sizes of thecrystal particles at the rim of the communication holes of the hydroxylapatite porous material of the 75% porosity (baked at 1,200° C. for 2hours in the air), at a position 0.5 μm away from the rim, at a position1 μm away from the rim, and at a position 1.5 μm away from the rimwere0.42 μm, 0.5 μm, and 0.55 μm, and 0.62 μm, respectively. Moreover, theaverage particle sizes of the crystal particles at the rim of thecommunication holes of the silicon carbide porous material of the 75%porosity (baked at 2300° C. for 2 hours in the reduced pressure argongas atmosphere), at a position 2 μm away from the rim, and at a position4 μm away from the rim were 0.49 μm, 4.38 μm, and 4.38 μm, respectively.

SUMMARY OF THE INVENTION

[0013] Accordingly, an object of the present invention is to provide aproduction method for a ceramic porous material having a high strengthfor its high porosity and the excellent transmissivity without the riskof generation of dusts.

[0014] A first aspect of the production method for a ceramic porousmaterial is a production method for a ceramic porous material comprisingthe steps of preparing a bubble-like slurry by mixing and whipping aceramic powder, a liquid medium, a dispersing agent, forming agent ifnecessary and a gellation main agent, adding and mixing a gellation subagent to the bubble-like slurry, pouring into a mold for obtaining agellation product, drying the gellation product for having a compacthaving a three dimensional mesh-like skeleton structure with a largenumber of substantially spherical adjacent cells communicating with eachother via communication holes, and sintering or fireing the compactdirectly, or temporarily baking (calcinating) the same before sinteringor fireing for obtaining a sintered or fired product, wherein the rim ofeach communication hole in the compact, the temporarily baked product orthe sintered or fired product is eliminated mechanically.

[0015] A second aspect of a production method for a ceramic porousmaterial is a production method for a ceramic porous material comprisingthe steps of preparing a bubble-like slurry by mixing and whipping aceramic powder, a liquid medium, a dispersing agent if necessary, aforming agent and a gellation main agent, adding and mixing a gellationsubagent to the bubble-like slurry, pouring into a mold for obtaining agellation product, drying the gellation product for having a compacthaving a three dimensional mesh-like skeleton structure with a largenumber of substantially spherical adjacent cells communicating with eachother via communication holes, and sintering or fireing the compactdirectly, or temporarily baking (calcinating) the same before sinteringor fireing for obtaining a sintered or fired product, wherein the rim ofeach communication hole in the compact, the temporarily baked product orthe sintered or fired product is eliminated chemically.

[0016] Moreover, a third aspect of a production method for a ceramicporous material is a production method for a ceramic porous materialcomprising the steps of preparing a bubble-like slurry by mixing andwhipping a ceramic powder, a liquid medium, a dispersing agent ifnecessary, a forming agent and a gellation main agent, adding and mixinga gellation sub agent to the bubble-like slurry, pouring into a mold forobtaining a gellation product, drying the gellation product for having acompact having a three dimensional mesh-like skeleton structure with alarge number of substantially spherical adjacent cells communicatingwith each other via communication holes, and sinterd or fired thecompact directly, or temporarily baking calcinating the same beforesintering or fireing for obtaining a sintered or fired product, whereinthe evaporation-condensation mechanism with respect to the crystalparticles at the rim of each communication hole is promoted during thesintering or fireing operation of the compact or the temporarily bakedproduct, or the re-sintering or re-fireing operation of the sintered orfired product. In addition, in the above-mentioned three methods, thedispersing agent is used when a large-sized product is manufactured, andotherwise it is omissible.

[0017] According to the above-mentioned ceramic porous material, thecrystal particle size in the entire skeleton structure can be even.

[0018] It is preferable that the skeleton structure itself includes onlythe closed cells or it has substantially no cells.

[0019] As the ceramic for forming the skeleton structure, alumina,alumina-silica, calcium phosphate based substance, silicon carbide,zirconia, or the like can be used.

[0020] In contrast, according to the first aspect of the productionmethod for a ceramic porous material, the abnormal part at the rim ofeach communication hole can be eliminated so that the hole size of thecommunication holes is made larger.

[0021] The mechanical elimination of the rim of each communication holecan be executed by permeating a liquid such as water or a gel such as anagar with a hard fine particle such as a diamond powder and a siliconcarbide powder dispersed through the compact, the temporarily bakedproduct, or the sintered or fired product.

[0022] Although the elimination of the rim of each communication holecan be executed also to the sintered or fired product, it is moreefficient to execute the same to the temporarily baked product with alow strength, and in the case of executing the same to the compact, aliquid medium not to dissolve the compact is used.

[0023] The permeating operation of the liquid or the gel with the hardfine particle dispersed through the compact, the temporarily bakedproduct or the sintered or fired product can be executed either from onedirection or from multiple directions.

[0024] It is necessary that the hard fine particle, or the like does notremain in the temporarily baked product or the sintered or fired productafter elimination of the rim of each communication hole. Therefore, itis preferable that the hard fine particle has a particle size largerthan the cell diameter in the skeleton structure (gap between theprimary particles) because the hard fine particle is in a state stuckbetween the primary particles in the skeleton structure in the case theyhave the substantially same size.

[0025] According to the second aspect of the production method for aceramic porous material, similar to the case of the first aspect, theabnormal part at the rim of each communication hole can be eliminated sothat the hole size of the communication holes is made larger.

[0026] The chemical elimination of the rim of each communication holecan be executed by soaking the temporarily baked product or the sinteredor fired product in phosphoric acid or sulfuric acid, or the like, ordissolution at a high temperature by a sodium borate fused salt.

[0027] This is because the abnormal part unstable in terms of shape hasa larger dissolution speed than that of the other parts.

[0028] It is also possible to promote the dissolution speed by heatingand pressuring the phosphoric acid(pressuring the phosphoric acid isdangerous) or the sulfuric acid at the time of the soaking operation.

[0029] Moreover, according to the third aspect of the production methodfor a ceramic porous material, the crystal particle size at the rim ofeach communication hole can be equivalent to the crystal particle sizeof the other parts.

[0030] The evaporation is carried out selectively quickly at a part witha high potential, that is, in the abnormal part, and the condensation iscarried out selectively at a part with a low potential, that is, in therecessed part.

[0031] The sintering, fireing, re-sintering, or re-fireing or re-bakingoperation is carried out at a high temperature of 1,800° C. or higher ina hydrogen gas atmosphere or in a vacuum atmosphere, or in an atmospherecontaining a halogen of a chlorine. According to the atmospheres, theevaporation-condensation mechanism promotion temperature is lowered byproduction of a volatile compound.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is an electron microscope photograph showing the crystalstructure of an alumina ceramic porous material baked at 1,200° C. for 2hours in the air without the mechanical process or the like; and

[0033]FIG. 2 is an electron microscope photograph showing the crystalstructure of the alumina ceramic porous material of FIG. 1 afterre-fireing at 1,840° C. for 10 hours in a hydrogen atmosphere.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, embodiments of the present invention will beexplained with reference to specific examples and comparative examples.

EXAMPLES 1 to 5, Comparative Example 1

[0035] First, a bubble-like slurry was prepared by mixing and agitating100 parts by weight of a low soda alumina having a 1 μm average particlesize as the ceramic powder, 20 parts by weight of ion exchange water asthe liquid medium, 1 part by weight of an ammonium polyacrylate as thedispersing agent, 0.5 part by weight of a triethanol amine laurylsulfate as the foaming agent, and 4 parts by weight of an epoxy resin asthe gellation main agent by an agitator while introducing the air.

[0036] Next, while agitating the bubble-like slurry, 1 part by weight ofan iminobispropyl amine as the gellation sub agent was added thereto.After pouring the same in a mold and passage of 30 minutes, thegellation proceeded sufficiently so as to obtain a gellation product.

[0037] Then, the gellation product was taken out from the mold and driedat 60° C. for whole day and night so as to obtain a compact (driedproduct).

[0038] The obtained compact has a three-dimensional mesh-like skeletonstructure with a large number of substantially spherical adjacent cellscommunicating with each other via communication holes.

[0039] Next, the compact was heated (temporarily baked) at 1,200° C. for2 hours in the air so as to obtain a temporarily baked product. It wasprocessed with a diamond grinding stone so as to obtain 6 pieces ofcolumnar temporarily baked product with a 50 mm diameter and a 100 mmlength.

[0040] In contrast, a cube-like test piece of a 2 mm side size was cutout from a part of the temporarily baked product and observed with anelectron microscope. It was found that the alumina crystal particles ofthe part except the rim of the communication holes in the skeletonstructure were grown up to about 1.5 μm, while those of the part of therim of the communication holes in the skeleton structure were grown upto about 1.0 μm.

[0041] Moreover, the cell distribution was measured with a mercurypressure penetrated porosimeter so as to find peaks at 0.3 μm and 50 to100 μm. As a result, it is learned that the gap between the aluminaprimary particles is 0.3 μm and the cell diameter is 50 to 100 μm, andthe minimum size of the communication hole is about 20 μm.

[0042] Next, 50 parts by weight of a silicon carbide powder having a 5μm average particle size, 50 parts by weight of ion exchange water and0.1 part by weight of an ammonium polyacrylate as the dispersing agentwere mixed so as to prepare a slurry. The slurry was sent with pressureat 30 cm/second flow rate by a pump comprising a circulation system forpermeating 5 pieces of the columnar temporarily baked product therewithfrom the longitudinal direction for 10 minutes, 1 hour, 2 hours, 5 hoursand 10 hours (examples 1 to 5). In contrast, the remaining one piece wasprovided as the temporarily baked product without permeation with theslurry (comparative example 1).

[0043] The 5 pieces of the temporarily baked product with the slurrypermeation were washed sufficiently with ion exchange water foreliminating the silicon carbide powder. After drying at 120° C. for 1hour, including the temporarily baked product without the slurrypermeation, they were fired at 1,600° C. for 2 hours in the air so as toobtain the fired products and obtain 6 pieces of alumina ceramic porousmaterials.

[0044] The average cell size of each of the obtained alumina ceramicporous materials was 150 μm. Moreover, the porosity, the existence orabsence of the abnormal part, the condensation strength, the pressureloss and the time to the particle number zero count were as shown in thetable 1.

[0045] As to the existence or absence of the abnormal part, a cube-liketest piece of a 2 mm side size was cut out form each alumina ceramicporous material and taking a scanning type electron microscopephotograph thereof for observing the rim of the communication holescommunicating the cells at a high magnification ratio of about 5,000times. Thereby, whether or not the crystal particle growth wasrestrained compared with the other parts of the skeleton structure wasobserved, and furthermore, the existence or absence of the abnormalitysuch as the cactus-like shape was observed.

[0046] As to the condensation strength, a short columnar-like shapedtest piece of a 10 mm diameter and a 10 mm height was cut out from eachalumina ceramic porous material with a diamond tool, and after a dryingoperation, the condensation strength was measured.

[0047] Moreover, as to the time to the particle number zero count, afterwashing the above-mentioned test pieces sufficiently with ion exchangewater, time until elimination of dust generation was measured with aparticle counter while applying the shock. TABLE 1 time to existence theor particle absence Condensa- number of the tion pressure zero porosityabnormal strength loss count (%) part (MPa) (KPa) (minute) example 60.2exist 350 0.9 5 1 example 61 absent 420 0.6 0.5 2 example 62 absent 4000.45 0.4 3 example 65 absent 400 0.3 0.3 4 example 70 absent 380 0.2 0.25 Compara- 60 exist 300 0.1 60 tive example 1

[0048] As it is shown in the table 1, in the case the abnormal part atthe rim of communication holes is eliminated by applying the mechanicalprocess, the porosity and the mechanical strength are made higher aswell as the transmission resistance is made dramatically smalleraccording to the enlargement of the communication hole diameteraccompanying the elimination of the abnormal part, and the particlegeneration was substantially eliminated.

EXAMPLES 6 TO 10

[0049] First, with reference to the examples 1 to 5, 5 compact pieceswere produced with different porosities in the substantially same mannertherewith. The compacts were temporarily baked so as to obtaincolumnar-shaped compacts. After the elimination process by permeationwith the silicon carbide slurry, they were made to have the sameporosity.

[0050] Next, in the same manner as in the examples 1 to 5, thetemporarily baked products were fired for providing the fired productsso as to obtain 5 pieces of alumina ceramic porous materials of a 60%porosity.

[0051] The porosity of the obtained alumina ceramic porous materials,the existence or absence of the abnormal part, the pressure loss and thetime to the particle number zero count were measured in the same manneras in the examples 1 to 5. Results are shown in the table 2 togetherwith those of the comparative example 1. TABLE 2 time to existence theor particle absence Condensa- number of the tion pressure zero porosityabnormal strength loss count (%) part (MPa) (KPa) (minute) example 60exist 350 0.9 5 6 example 60 absent 550 0.8 2 7 example 60 absent 6000.7 1 8 example 60 absent 800 0.6 0.5 9 example 60 absent  1000 0.5 0.210 Compara- 60 exist 300 1 60 tive example 1

[0052] As it is shown in the table 2, in the case the abnormal part witha small crystal particles at the rim of the communication holes iseliminated by applying the mechanical process so as to have the crystalparticle size at the rim of the communication holes substantiallyequivalent to the crystal particle size in the other parts of theskeletons structure, the mechanical strength of the alumina ceramicporous materials of the same cell size and the porosity can dramaticallybe improved.

[0053] The air transmission amount and the pressure loss of the aluminaceramic porous material were measured so as to confirm the pressure lossinversely proportional to the square value of the average value of thecommunication hole size.

EXAMPLES 11 TO 15, COMPARATIVE EXAMPLE 2

[0054] First, a bubble-like slurry was prepared by mixing and agitating100 parts by weight of a silicon carbide powder having a 0.5 μm averageparticle size as the ceramic powder, 40 parts by weight of ion exchangewater as the liquid medium, 1.0 parts by weight of a triethanol aminelauryl sulfate as the foaming agent, 2 parts by weight of a carbon blackhaving a 260 m²/g specific surface area and 0.5 part by weight of aboron carbide having a 1.6 μm average particle size as the sinteringauxiliary agent, and 6 parts by weight of a polyethylene imine as thegellation main agent by an agitator while introducing the air.

[0055] Next, while agitating the bubble-like slurry, 2 parts by weightof an epoxy resin as the gellation sub agent was added thereto. Afterpouring the same in a mold and passage of 30 minutes, the gellationproceeded sufficiently so as to obtain a gellation product.

[0056] Then, the gellation product was taken out from the mold and driedat 60° C. for whole day and night so as to obtain a compact (driedproduct).

[0057] The obtained compact has a three-dimensional mesh-like skeletonstructure with a large number of substantially spherical adjacent cellscommunicating with each other via communication holes.

[0058] Next, the compact was heated (temporarily baked) at 1,800° C. for1 hour in an argon gas atmosphere so as to obtain a temporarily bakedproduct. It was processed with a diamond grinding stone so as to obtain6 pieces of columnar temporarily baked product with a 50 mm diameter anda 100 mm length.

[0059] In contrast, a rectangular parallelopiped-like test piece of a 5mm longitudinal size, a 5 mm lateral size and a 10 mm length was cut outfrom a part of the temporarily baked product and the cell distributionwas measured with a mercury pressure penetrated porosimeter so as tofind peaks at 0.02 μm, 0,2 μm, and 10 μm.

[0060] Next, as in the examples 1 to 5, 50 parts by weight of a siliconcarbide powder having a 5 μm average particle size, 50 parts by weightof ion exchange water and 0.1 part by weight of an ammonium polyacrylateas the dispersing agent were mixed so as to prepare a slurry. The slurrywas sent with pressure at 30 cm/second flow rate by a pump comprising acirculation system for permeating 5 pieces of the columnar temporarilybaked product therewith from the longitudinal direction for 10 minutes,1 hour, 2 hours, 5 hours and 10 hours (examples 11 to 15). In contrast,the remaining one piece was provided as the temporarily baked productwithout permeation with the slurry (comparative example 2).

[0061] As in the examples 1 to 5, the 5 pieces of the temporarily bakedproduct with the slurry permeation were washed sufficiently with ionexchange water for eliminating the silicon carbide powder. After dryingat 120° C. for 1 hour, including the temporarily baked product withoutthe slurry permeation, they were sintered at 2, 200° C. for 1 hours inan argon gas atmosphere so as to obtain the baked products and obtain 6pieces of silicon carbide ceramic porous materials.

[0062] The average cell size of each of the obtained silicon carbideceramic porous materials was 100 μm. Moreover, the porosity, theexistence or absence of the abnormal part, the condensation strength,the pressure loss and the time to the particle number zero count weremeasured as in the examples 1 to 5. Results are shown in the table 3.TABLE 3 time to existence the or particle absence Condensa- number ofthe tion pressure zero porosity abnormal strength loss count (%) part(MPa) (KPa) (minute) example 55.2 exist 520 1.1 5 11 example 56 absent800 0.8 0.3 12 example 57 absent 900 0.65 0.2 13 example 60 absent  10000.4 0.1 14 example 64 absent 950 0.3 0.1 15 Compara- 55 exist 500 1.2 75tive example 2

[0063] As it is shown in the table 3, in the case the abnormal part atthe rim of communication holes is eliminated by applying the mechanicalprocess, the porosity and the mechanical strength are made higher aswell as the transmission resistance is made dramatically smalleraccording to the enlargement of the communication hole diameteraccompanying the elimination of the abnormal part, and the particlegeneration was substantially eliminated.

EXAMPLE 16

[0064] First, the alumina ceramic porous material of the comparativeexample 1 was processed into a rectangular parallelepiped-like shape ofa 1 cm square and a 10 cm length. A slurry with a sodium borate powderdispersed by 30% in an acetone was poured thereon for introducing thesodium borate slurry into the cells of the alumina ceramic porousmaterial.

[0065] Next, after dying the acetone, it was introduced into a furnacekept at 1,000° C. for fusing the sodium borate. After maintaining thesame in the furnace for 10 minutes, it was taken out from the furnaceand cooled down in the air. Then, it was boiled in a dilutedhydrochloric acid for 2 hours for dissolving and eliminating the sodiumborate so as to obtain an alumina ceramic porous material.

[0066] The porosity, the existence or absence of the abnormal part, thecondensation strength, the pressure loss and the time to the particlenumber zero count were measured as in the examples 1 to 5. Results areshown in the table 4 together with those of the comparative example 1.TABLE 4 time to existence the or particle absence Condensa- number ofthe tion pressure zero porosity abnormal strength loss count (%) part(MPa) (KPa) (minute) example 75 absent 500 0.1 0.1 16 Compara- 60 exist300 1 60 tive example 1

[0067] As it is shown in the table 4, by eliminating the abnormal partby applying the chemical process, the porosity and the mechanicalstrength are made higher as well as the particle generation iseliminated, and the transmission resistance is made smaller.

EXAMPLES 17, 18

[0068] The temporarily baked product of the comparative example 1 andthe fired product of the comparative example 1 were fired or re-fired at1,900° C. in a hydrogen gas atmosphere for 5 hours for providing a bakedproduct or a re-baked product so as to obtain an alumina ceramic porousmaterial, respectively.

[0069] The crystal particles of both of the obtained ceramic porousmaterials had grain growth to about 20 μm. Moreover, the porosity, theexistence or absence of the abnormal part, the condensation strength,the pressure loss and the time to the particle number zero count weremeasured as in the examples 1 to 5. Results are shown in the table 5together with those of the comparative example 1. TABLE 5 time toexistence the or particle absence Condensa- number of the tion pressurezero porosity abnormal strength loss count (%) part (MPa) (KPa) (minute)example 60 absent 400 0.1 0.1 17 example 60 absent 400 0.1 0.1 18Compara- 60 exist 300 1 60 tive example 1

[0070] As it is shown in the table 5, by denaturing the abnormal part byprocessing the temporarily baked product or the fired product in a hightemperature hydrogen gas so as to have the crystal particle size in theentire skeleton structure evenly, a high porosity and a high mechanicalstrength can be provided as well as the particle generation waseliminated, and the transmission resistance is made smaller.

[0071] The particle structure of the alumina ceramic porous materialbaked at 1,600° C. for 2 hours in the air without the mechanical processis as shown in FIG. 1. Moreover, the crystal structure of theabove-mentioned alumina ceramic porous material after re-fireing at1,840° C. for 10 hours in a hydrogen atmosphere is as shown in FIG. 2.

[0072] As it is shown in the FIG. 2, by the process in the hightemperature hydrogen gas, the entire crystal particle size is madesubstantially equivalent.

[0073] As heretofore explained, according to a ceramic porous materialand a production method therefore of the present invention, since theentire crystal particle size of the skeleton structure can be even, toprovide a ceramic porous material which has a high strength, though ithas a high porosity, and which is excellent in permeability without dustgeneration.

What is claimed is:
 1. A production method for a ceramic porous materialcomprising the steps of preparing a bubble-like slurry by mixing andwhipping a ceramic powder, a liquid medium, a dispersing agent ifnecessary, a foaming agent and a gellation main agent, adding and mixinga gellation sub agent to the bubble-like slurry, pouring into a mold forobtaining a gellation product, drying the gellation product for having acompact having a three dimensional mesh-like skeleton structure with alarge number of substantially spherical adjacent cells communicatingwith each other via communication holes, and sintering or fireing thecompact directly, or temporarily baking (calcinating) the same beforesintering or fireing for obtaining a sintered or fired product and thenbaking the same for obtaining a baked product, wherein the rim of eachcommunication hole in the compact, the temporarily baked product or thesintered or fired product is eliminated mechanically.
 2. A productionmethod for a ceramic porous material comprising the steps of preparing abubble-like slurry by mixing and whipping a ceramic powder, a liquidmedium, a dispersing agent (if necessary), a forming agent and agellation main agent, adding and mixing a gellation sub agent to thebubble-like slurry, pouring into a mold for obtaining a gellationproduct, drying the gellation product for having a compact having athree dimensional mesh-like skeleton structure with a large number ofsubstantially spherical adjacent cells communicating with each other viacommunication holes, and sintering or fireing the compact directly, ortemporarily baking (calcinating) the same before sintering or fireingfor obtaining a sintered or fired product, wherein the rim of eachcommunication hole in the compact, the temporarily baked product or thesintered or fired product is eliminated chemically.
 3. A productionmethod for a ceramic porous material comprising the steps of preparing abubble-like slurry by mixing and whipping a ceramic powder, a liquidmedium, a dispersing agent if necessary, a forming agent and a gellationmain agent, adding and mixing a gellation subagent to the bubble-likeslurry, pouring into a mold for obtaining a gellation product, dryingthe gellation product for having a compact having a three dimensionalmesh-like skeleton structure with a large number of substantiallyspherical adjacent cells communicating with each other via communicationholes, and sintering or fireing the compact directly, or temporarilybaking (clcinating) the same before sintering or fireing for obtaining asintered or fired product, wherein the evaporation-condensationmechanism with respect to the crystal particles at the rim of eachcommunication hole is promoted during the sintering or fireing operationof the compact or the temporarily baked product, or the re-sintering orre-fireing operation of the sintered or fired product.